1. Field of the Invention
The present invention relates to a motor and a disk drive apparatus.
2. Description of the Related Art
Conventionally, a disk drive apparatus such as a hard disk drive apparatus or the like is equipped with a spindle motor for rotating a disk. The disk drive apparatus includes a disk, a housing, a stator, a FPC (Flexible Printed Circuit), and so forth. The housing includes a cover, a base plate, and so forth.
In recent years, the disk drive apparatus is required to become smaller in height and size. Particularly, in order to further reduce the height of a 2.5 inch type disk drive apparatus having a thickness of 7 mm or less, which belongs to small-size disk drive apparatuses, it is necessary to reduce the thickness of a housing or a motor arranged within the housing. In general, the motor includes a rotor hub, coils, a stator core, a wiring substrate, a base plate, etc. When assembling the motor, these components are arranged to axially overlap with one another. For the sake of reducing the thickness of the motor, these components need to be made thin. However, if an attempt is made to reduce the overall height of the motor by reducing the turn number of the coils or the lamination thickness of the stator core, the magnetic flux generated in the stator during the operation of the motor becomes reduced such that the torque constant is reduced. It is therefore impossible to obtain the torque required to rotate the disk attached to the rotor hub.
In order to reduce the height of the motor, it is therefore necessary to pay attention to, among the components of the motor, the base plate which dominates a large portion of the axial dimension of the motor. However, if the base plate is merely made thin, the rigidity of the base plate is reduced to a great extent. As a result, if a shocking force is applied from the outside to the base plate, it is likely that the base plate will be broken and that the disk arranged within the housing will be damaged.
Accordingly, a demand has existed for a structure capable of increasing the rigidity of the base plate while reducing the overall height of the motor.